In recent years, DVD players have remarkably come into wide use. One reason for this lies in ease of usage at high-speed playback, instant access to specific video or audio and the like. This greatly relies upon information of a navigation pack that is defined in DVD video format. The navigation pack is located at the head of a VOBU (Video Object Unit) which is a data unit defined by DVD standards. In the navigation pack of each VOBU, positional information indicating positions of plural VOBUs which are located forward and backward of this VOBU is included. Therefore, in the DVD player, the playback position can be jumped to a desired position instantaneously. This is because DVD video data is ROM data and positional information of a VOBU (hereinafter, referred to as a future VOBU) which will be processed later than a target VOBU to be processed can be known at the authoring. The VOBU is composed of one or more GOPs (a GOP is a data unit in which random access is performed) and, for purposes of explanation, hereinafter assume that a VOBU is a GOP.
In recent years, systems in which AV data (audio/video data) is recorded in real time like DVD recorders or HDD recorders have become widely available. However, in these systems, positional information of future data (data located backward of data which is being recorded at the present time) cannot be written. In a case where data are all recorded at a fixed rate (CBR), this positional information can be written, while in this case the compression efficiency is undesirably reduced. More specifically, systems which record data at variable rates (VBR) in real-time recording devices, such as a DVD recorder and a HDD recorder, include no means for recording information concerning future data like the data recorded in the navigation pack.
In addition, as methods for dubbing digital signals which are temporarily recorded in a HDD, there are conceivable a method by which digital data is restored to analog data and then the analog data is dubbed, and a method by which data is dubbed in its original signal format (digital format). However, it is desirable that the amount of information should be reduced or the signal format should be converted, according to the capacity of a medium onto which data is dubbed (dubbing destination).
Also in the real-time recording devices, a method for recording the positional information of future data corresponding to the navigation pack of DVD video has been demanded.